ProCurve 2610-PWR Informations techniques télécharger pdf (Page 115)

Spanning-Tree Operation

The RSTP (802.1w) and STP (802.1D) Spanning Tree Options

Note for 8 02.1 D

and 802.1w

Spann ing-Tree

Operation

You should enable spanning tree operation in any switch that is part of a

redundant physical link (loop topology). (ProCurve recommends that you do

so on all switches belonging to a loop topology.) This topic is covered in more

detail under “How STP and RSTP Operate” on page 5-9.

As recommended in the IEEE 802.1Q VLAN standard, the switches covered

by this guide use single-instance STP for 802.1D and 802.1w spanning-tree

operation. (In this case, the switch generates untagged Bridge Protocol Data

Units—BPDUs.) This implementation creates a single spanning tree to make

sure there are no network loops associated with any of the connections to the

switch, regardless of whether multiple VLANs are configured on the switch.

Thus, when using 802.1D or 802.1w spanning tree, these switches do not

distinguish between VLANs when identifying redundant physical links. In this

case, if VLANs are configured on the switch, see “STP Operation with 802.1Q

VLANs” on page “RSTP and STP Operation with 802.1Q VLANs” on page 5-9.

The RSTP (802.1w) and STP (802.1D)

Spanning Tree Options

Caution Spanning tree interprets a switch mesh as a single link. Because the switch

automatically gives faster links a higher priority, the default STP or RSTP

parameter settings are usually adequate for spanning tree operation. Also,

because incorrect STP or RSTP settings can adversely affect network perfor-

mance, you should not make changes unless you have a strong understanding

of how spanning tree operates.

In a mesh environment, the default RSTP timer settings (Hello Time and

Forward Delay) are usually adequate for RSTP operation. Because a packet

crossing a mesh may traverse several links within the mesh, using smaller-

than-default settings for the RSTP Hello Time and Forward Delay timers can

cause unnecessary topology changes and end-node connectivity problems.

For more on STP and RSTP, see the IEEE 802.1D and 802.1w standards.

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ProCurve 2610-PWR Informations techniques Page 115